The present invention relates to the general field of stator ring support spacers for a high-pressure turbine of a turbomachine. More particularly, the invention provides a device for holding a spacer sector so that said spacer sector is locked axially on the stator, and for providing thermal protection.
With reference to FIG. 3, the high-pressure turbine 100 of a turbomachine consists, in particular, of a plurality of rotor blades 102 disposed in a flow channel 105 for hot gas coming from a combustion chamber (not shown).
A plurality of stator blades 104 that constitute a high-pressure distributor are also disposed in the gas channel 105, upstream from the rotor blades 102 of the turbine.
The rotor blades 102 of the turbine are surrounded by a stator ring made up by a plurality of ring sectors 106. Said ring sectors 106 are secured to a casing 108 of the turbine by means of a plurality of spacer sectors 110.
The ring sectors 106 define clearance J at the tips 102a of the rotor blades 102 of the turbine, which clearance needs to be as small as possible in order to increase the efficiency of the turbine.
To that end, a clearance J tuning device 112 is mounted around the casing 108 of the turbine. Said tuning device 112 consists, in particular, of annular air flow ducts 114 that discharge air onto annular ridges 116 of the casing in order to change their temperature.
Depending on the requirements in terms of tuning the clearance J, varying the temperature of the ridges 116 causes the casing 108 to expand or to contract thermally, which increases or decreases the diameter of the stator ring.
Such an arrangement of the high-pressure turbine presents drawbacks in terms of the casing 108 heating and in terms of holding the spacer sectors 110 axially.
In practice, it has indeed been found that the portion of the casing 108 that is located upstream from the ridges 116 heats due to thermal radiation from the stator blades 104 of the high-pressure distributor.
Said thermal radiation (represented by arrows 118), is caused by the high temperatures of the combustion gas and propagates down the thermal gradient from the stator blades 104 of the high-pressure distributor to the casing. Heating of the casing is particularly detrimental to the lifetime of the turbine.
It has also been found that there is a problem of holding spacer sectors 110 axially. More particularly, spacer sectors on the casing 108 are not held axially upstream. That results in said spacer sectors running the risk of not being held radially.